Coaxial Cable With Foamed Insulation

1 . A coaxial cable comprising:

(a) an inner conductor,

(b) an outer conductor, and

(c) a foamed insulation, surrounding the inner conductor, prepared from an insulation composition comprising

(i) a foamable polymer,

(ii) a foaming agent, and

(iii) a particulate, non-halogenated, non-heterocyclic polyolefinic nucleating agent having a particle size and a surface tension which are effective for foaming the foamable polyolefin polymer at an expansion rate of at least about 70 percent.

2 . The coaxial cable of claim 1 , wherein the nucleating agent is effective for providing an expansion rate of greater than about 80 percent.

3 . The coaxial cable of claim 1 , wherein the nucleating agent has an average particle size in the range from 0.1 μm to 100 μm.

4 . The coaxial cable of claim 1 , wherein the nucleating agent has a surface tension of less than about 30 dynes/cm.

5 . The coaxial cable of claim 1 , wherein the nucleating agent being added in an amount from 0.01 to 1.0 weight percent based on the weight of the insulation composition.

6 . The coaxial cable of claim 1 , wherein the nucleating agent has a melting point in the range between 130 degrees Celsius to 240 degrees Celsius.

7 . The coaxial cable of claim 1 , wherein the nucleating agent has a melting point at least 15 degrees Celsius higher than the melting point of the foamable polymer.

8 . The coaxial cable of claim 1 , wherein the nucleating agent is selected from the group consisting of poly 4-methylpentene-1, poly 4-methylhexene-1, poly 5-methylhexene-1, poly 4-methylheptene-1, poly 5-methylheptene-1, poly 6-methylheptene-1, and mixtures thereof.

9 . An insulation composition comprising:

(a) a foamable polymer,

(b) a foaming agent, and

(c) a particulate, non-halogenated, non-heterocyclic polyolefinic nucleating agent having a particle size and a surface tension which are effective for foaming the foamable polyolefin polymer at an expansion rate of at least about 70 percent.

10 . The insulation composition of claim 9 , wherein the nucleating agent is effective for providing an expansion rate of greater than about 80 percent.

11 . The insulation composition of claim 9 , wherein the nucleating agent has an average particle size in the range from 0.1 μm to 100 μm.

12 . The insulation composition of claim 9 , wherein the nucleating agent has a surface tension of less than about 30 dynes/cm.

13 . The insulation composition of claim 9 , the nucleating agent being added in an amount from 0.01 to 1.0 weight percent based on the weight of the insulation composition.

14 . The insulation composition of claim 9 , wherein the nucleating agent has a melting point in the range between 130 degrees Celsius to 240 degrees Celsius.

15 . The insulation composition of claim 9 , wherein the nucleating agent has a melting point at least 15 degrees Celsius higher than the melting point of the foamable polymer.

16 . The insulation composition of claim 9 , wherein the nucleating agent is selected from the group consisting of poly 4-methylpentene-1, poly 4-methylhexene-1, poly 5-methylhexene-1, poly 4-methylheptene-1, poly 5-methylheptene-1, poly 6-methylheptene-1, and mixtures thereof.